A barber/beauty chair having a seat part which a person under hairdressing sits on and is moved upward and downward by a hoisting/lowering mechanism has been widely used in a beauty salon or the like. The up and down operation of the barber/beauty chair is performed by a method for hoisting/lowering the seat part directly by an oil hydraulic cylinder or a method for hoisting/lowering the seat part by combining the oil hydraulic cylinder and a parallel link.
The barber/beauty chair using the method for hoisting/lowering the seat part directly by the oil hydraulic cylinder has an oil hydraulic cylinder device on a base of the barber/beauty chair and the seat part at a tip side of the oil hydraulic cylinder device. The height of the seat part is adjusted by expanding or contracting the oil hydraulic cylinder.
Generally, it is desired that an ascendable/descendable seat part can be moved into a position as low as possible in order to set the seat part in a position so that a person under hairdressing can easily sit. On the other hand, it is desired that the seat part can be moved as widely as possible so that a hairdresser sets the head of the person under hairdressing in a position where the hairdresser can easily work.
When using the above-mentioned barber/beauty chair, in order to make the lowest position of the seat part lower, a body of the cylinder device which is situated between the base and the seat part should be made shorter. However, the cylinder device having a shorter body has a shorter piston part, resulting in a shorter extendable stroke, whereby the seat can be moved less widely. Therefore, it is difficult to make the lowest position of the seat part lower as well as extend the movable area of the seat part.
On the other hand, the barber/beauty chair using the method for hoisting/lowering the seat part by combining the oil hydraulic cylinder and the parallel link can make the lowest position of the seat part lower as well as extend the movable area of the seat part.
FIG. 5 is a sectional view illustrating a hoisting/lowering mechanism of a prior art barber/beauty chair which uses the method for hoisting/lowering a seat by combining the oil hydraulic cylinder and the parallel link.
In the figure, reference numeral 1 designates a hoisting/lowering mechanism of the barber/beauty chair. The hoisting/lowering mechanism 1 comprises a base 2, a support 3 stood on the base 2, an upper link 4 having one end attached to the support 3, a lower link 5 which is disposed below the upper link 4 and has one end attached to the support 3, a seat supporting arm 7 which is attached to the other end of the upper link 4 and the other end of the lower link 5, a pedestal part 9 attached to the seat supporting arm 7, an oil hydraulic cylinder 10 attached to the base 2, and an oil hydraulic pump 13.
The upper link 4 and the lower link 5 are parallel links which are disposed in parallel with each other. One end of each link is rotatably connected to the support 3 by a shaft 6 and the other end of each link is rotatably connected to the seat supporting arm 7 by a shaft 8. In addition, a piston rod of the oil hydraulic cylinder 10 is rotatably connected by a shaft 12 to a bracket 11 which is attached to the upper link 4.
Further, a seat which a person under hairdressing sits on is attached to an upper part of the pedestal part 9, but it is not shown in the figure.
Hereinafter, the noising/lowering operation of the pedestal part 9 by the hoisting/lowering mechanism 1 will be described.
In order to move the pedestal part 9 upward from the lowest position as shown in FIG. 5, the oil hydraulic pump 13 applies the pressure to the oil hydraulic cylinder 10 and the piston rod of the oil hydraulic cylinder 10 is expanded. Thereby, the upper link 4 and the lower link 5 rotate upwardly and the pedestal part 9 is moved upward with always keeping a horizontal state. A hairdresser moves the pedestal part 9 until the position of the head of the person sitting on the seat equipped on the upper part of the pedestal part 9 reaches a position which is suitable for works such as hairdressing.
On the other hand, when the pedestal part 9 is moved downwardly, the oil hydraulic pump 13 decreases the pressure of the oil hydraulic cylinder 10 and the piston rod of the oil hydraulic cylinder 10 is contracted. Thereby, the upper link 4 and the lower link 5 rotate downwardly and the pedestal part 9 is moved downwardly with always keeping the horizontal state.
A movable area of the pedestal part 9 can be adjusted by setting appropriately a connection position between the piston rod of the oil hydraulic cylinder 10 and the upper link 4. That is, the movable area of the pedestal part 9 becomes wider as the connection position approaches the shaft 6 while it becomes narrower as the connection position approaches the shaft 8.
In this way, according to the barber/beauty chair using the method for hoisting/lowering the seat by combining the oil hydraulic cylinder and the parallel link, the movable area of the pedestal part can be set arbitrarily by adjusting the connecting position between the oil hydraulic cylinder and the parallel link, whereby the lowest position of the seat of the barber/beauty chair can be made sufficiently low and the movable area of the seat can be wider.
In a beauty salon or the like, the hairdressing is usually performed together with hair washing and a barber/beauty chair having an ascendable/descendable seat is used also in washing hair. In this case, there are following problems.
When the pedestal part 9 is hoisted/lowered by the hoisting/lowering mechanism as shown in FIG. 5, the hoisting/lowering movement of the pedestal part 9 corresponds to rotational motions of the upper link 4 and the lower link 5 around the shaft 6. Therefore, there is displacement 1 between a center position A of the pedestal part 9 in the lowest position and a center position B of the pedestal part 9 situated at a height.
Since this displacement 1 varies in accordance with an amount of the hoisting/lowering movement of the seat of the barber/beauty chair, the distance between the seat of the barber/beauty chair and a hair washing stand varies during the hoisting/lowering operation, whereby it is difficult to adjust the height of the seat from the hair washing stand.
Further, when the displacement is quite large, the barber/beauty chair itself may be unstable. Therefore, it is necessary to consider the displacement sufficiently in designing the barber/beauty chair.